[PATCH 3.12 51/62] tg3: avoid double-freeing of rx data memory

Greg Kroah-Hartman
2013-12-10T08:09:37Z

From: Ivan Vecera <ivecera@redhat.com>

commit 85aec73d595b8847f9c4ea571deb127913f0d508 upstream.

If build_skb fails the memory associated with the ring buffer is freed but
the ri->data member is not zeroed in this case. This causes a double-free
of this memory in tg3_free_rings->... path. The patch moves this block after
setting ri->data to NULL.
It would be nice to fix this bug also in stable >= v3.4 trees.

Cc: Nithin Nayak Sujir <nsujir@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/ethernet/broadcom/tg3.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -6848,12 +6848,6 @@ static int tg3_rx(struct tg3_napi *tnapi
pci_unmap_single(tp->pdev, dma_addr, skb_size,
PCI_DMA_FROMDEVICE);

- skb = build_skb(data, frag_size);
- if (!skb) {
- tg3_frag_free(frag_size != 0, data);
- goto drop_it_no_recycle;
- }
- skb_reserve(skb, TG3_RX_OFFSET(tp));
/* Ensure that the update to the data happens
* after the usage of the old DMA mapping.
*/
@@ -6861,6 +6855,12 @@ static int tg3_rx(struct tg3_napi *tnapi

ri->data = NULL;

+ skb = build_skb(data, frag_size);
+ if (!skb) {
+ tg3_frag_free(frag_size != 0, data);
+ goto drop_it_no_recycle;
+ }
+ skb_reserve(skb, TG3_RX_OFFSET(tp));
} else {
tg3_recycle_rx(tnapi, tpr, opaque_key,
desc_idx, *post_ptr);